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Fires threaten water quality

Staff Writer

SUN photo/Mike Pierce

SUN photo/Mike Pierce

Not only are the fires threatening the landscape, they are also threatening water quality in Pagosa Country.

With monsoon season approaching, residents can expect to find silt, ash and debris in their water sources. This turbidity can impact the capacity of reservoirs as well as the quality of water.

Until the monsoon arrives, conditions are perilously dry.

According to the Natural Resources Conservation Service (NRCS), weather patterns established in late April continued during May with persistent dry conditions in southwest Colorado. The Upper Rio Grande combined with the San Juan, Animas, San Miguel and Dolores basins were at 2 percent of the June snowpack median. As of June 2, Wolf Creek Summit was snow free.

Mountain precipitation recorded in the basins as of May was 60 percent of average. Reservoir storage in the basins have remained constant at 67 percent of average with a slight increase during the month of May due to runoff.

At this time, the forecast for streamflows in the basins remains well below average at 120 cubic feet per second (CFS).

“It is unlikely that the state will see much relief from drought conditions this year,” the NRCS website read.

When rain does arrive, trouble could begin on another front.

According to U.S. Forest Service hydrologist Rebecca Smith, the West Fork Fire is mostly burning on the Rio Grande side of the Divide, however, it is slowly burning around the edges within the West Fork drainage. There have been 16,000-plus acres burned in the West Fork drainage, which includes areas above Pagosa Area Water and Sanitation District’s (PAWSD) intake.

With the lack of vegetation due to fires in the forest watershed, the runoff caused by severe rainstorms increases in speed and has little to slow it down, leading to the potential of flooding and soil erosion. According to the Burned Area Emergency Response Team (BAER) in their report on the Missionary Ridge Fire aftermath, the amount of runoff depends on the area of the watershed, including how steep it is, as well as the severity of the burns.

BAER also includes that another condition that affects the severity of runoff during these storms is the water-repellant soils caused by burned plant materials. Gasses from the burned plant materials form a waxy layer on the soil surface causing the soil to repel water. With less water being soaked into the soil, the rate of runoff increases and surviving plants have a difficult time obtaining a water source.

These effects of wildfire on the surface means an increase in flooding, sediments, ash, and debris. BAER notes that the effects of the runoff can be severe and life threatening.

“Water is dropping rapidly right now that the snow is gone and a lot of streams have dried up early and are drying up now,” Bob Formwalt of the Division of Water Resources explained. “The problem that we are seeing, and it hasn’t happened yet, but it will happen, is that once all of this (the fires) cools off and the weather changes and we get our thunderstorms that we get particularly in July, those water sheds in West Fork and East Fork are going to be damaged to the point that there is not going to be much holding that water back. It is going to get worse when the water starts flowing with ash when the rains hit. People need to be preparing themselves for that flow.”

It was revealed at the June 25 PAWSD board meeting that the U.S. Forest Service as well as PAWSD staff and engineers are working on preparations.

The Forest Service will utilize what is called a “Burned Emergency Response Team.” The team will assess the damage from the fire on the West Fork, analyzing the effects of the fire damage as well as predicting what will happen when it begins to rain. They will then  request funding from the regional office for any treatments on effects.

“In terms of the water system, I would expect pretty substantial effects to water quality beginning with the first rain,” Smith said. “The first thing that will happen is that the ash will come off of the fire, the water is going to turn black, it’s going to have a lot of turbidity, and then we will also get some sediment coming off in the later rains. The greatest effect will be the higher intensity but shorter duration storms, such as thunderstorms. Up in the water shed, it’s pretty steep. There’s a lot of burned trees that are going to come down the river, rocks and sediments and stuff like that. Most of that will be deposited upstream in the intake, because you have a fairly long distance and a low gradient, so the larger material will be deposited upstream.”

“Were you able to do mitigation in the wilderness?” Jeff Shamburg, project engineer for Bartlett and West asked.

“It depends,” said Smith. “It is a little more restrictive. These are emergency treatments … we won’t have any heavy equipment in there. We couldn’t with the terrain, anyway. It’s pretty inaccessible and, by itself, limits the potential treatments, and treatments for water quality. You are going to have water quality impacts.”

According to Smith, at this time there is no concern with the Windy Pass Fire affecting the watersheds. Smith explains that this could change due to the fire still burning and not knowing how much more the fire will expand.

When asked about the potential effects on the San Juan River, Smith explained that, because of dilution from other drainages, there will be some impacts, but they will be less severe.

“We’re really concerned about that first runoff of the ash,” PAWSD District Manager Ed Winton said, “Our contingency plan is to shut the plant down until it passes and then we could feed the town from up here (the plant on Lyn Avenue), but doing that we would have to impose some type of creative water management because we will only be able to feed one third of what is required of the town.”

“That by itself seems pretty frightening, but as a management issue, over a twenty-four hour period we have the ability to run that Snowball Plant (near town) for a little while off of the pond after we shut that intake down,” Shamburg said, “We have the ability, not for long. We also have storage in the tanks that lasts a certain amount of time, so you could get through an ash event and get the plant fired back up before you ever see a crisis really hit. Its going to be management issues; its going to be forecasting how long the plant is going to be down. Do we need to have some sort of mitigation steps, or not? If it’s a twelve-hour event we can certainly get the plant back up and running and people would never even know it happened.”

PAWSD plans to invest in a gauge that will be placed at the burn area in order to measure the amount of rain that falls.

“The equipment that we are looking at will determine the rate of the storm, how fast the storm is coming, is it a soft rain or it is a hard downpour?” Winton said. “The hard downpour is going to be a trigger for us to kind of giddy up; the soft rain, like she (Smith) said, is almost beneficial.”

According to Smith, the effects of the fire could be seen in the water supply for one to three years.

“Are there any cost effective mitigating measures that we can take that would reduce the risk to the intake?” director Roy Vega asked. “Is there any mesh that you can float on the stream that would catch the turbidity? For example, are there any screens? Should we be thinking about helping to revegetate?”

“What we have done is we have proactively gone out and we have built a jetty around our intakes to take care of the debris,” Said Winton. “The ash will still be a problem so once we get through the ash, however long it is going to be, we can deal with the debris.”

“One of the things that is advantageous is we don’t have to worry about the water running through and contaminating our reservoir. We can pick and choose when we can put water into the reservoir.

“We are in the process of letting people know that they might experience pressure changes, lower pressure, or pressure loss at some time. Or we may ask them, ‘Please don’t water your plants or wash your car.’ With the help of the Forest Service we can kind of predict how long it is going to transpire.

“We don’t want everyone to panic and say that this is an emergency — that we have to do this, we have to do that … because it’s a critical situation to deliver the same quality water that we do on a daily basis, and that is what we are going to strive to do.

“We want to be proactive, we want to get it done. We don’t want the storm to come and then have people lose water pressure and not know what is going on. We know it’s coming; we’re being proactive, we’re taking everything ahead of time and our objective is to provide the same quality water during the event as we do every day.”

According to the National Oceanic and Atmospheric Administration (NOAA), as of June 26 the forecast for the next seven days in the region shows high temperatures in the 90s and high 80s. On Friday, there is a 20-percent chance of thunderstorms.

“It’s something for everyone to be thinking about. This community will be facing it,” Formwalt said of the problem with rainfall and fire areas. “It is out there and it could be a threat. It’s time to think about what the future holds and it may not be very pretty. It (the ash) may settle and not wash down, but we need to look at the bad side and be prepared for it. I don’t want to be an excitist, but we need to be thinking about it.

“If it should happen to be dry the rest of the summer and the ash sits on the ground until the snow falls, then it may not be as bad as it would be if we had the hard summer rains that we usually get. There isn’t any vegetation to hold the stuff back. I hate to be down about it, but I think that is the reality.”

Melissa.Stedman@pagosasun.com

This story was posted on June 27, 2013.